The objective of this project is to continue investigating the role of the central nervous system in relation to immune processes. A review of the literature and the results of studies carried out by the investigators have indicated that the central nervous system modifies the course of certain immune mechanisms in the guinea pig. During the coming year the applicants plan to pursue in a systematic manner the study of the effect of anterior hypothalamic ablation on various mechanisms involved in immediate hypersensitivity. Experiments will be undertaken to assess the effect of the hypothalamic lesions on the passive cutaneous anaphylactic response in guinea pigs injected with graded amounts of rabbit antiovalbumin. Similar studies will be conducted on the effect of hypothalamic lesions on the skin sensitivity of guinea pigs to graded amounts of exogenous histamine. These studies will complement the work carried out this year contributing to the understanding of mechanisms of action of anterior hypothalamic lesions on immune phenomena.